Japanese Patent Application Publication No. 2010-264534 provides an impact driver that performs a fastening work by rotating a hammer in only forward direction. The impact driver can provide a strong fastening force although noise during fastening work is loud.
On the other hands, Japanese Patent Application Publication No. 2011-62771 provides an electronic pulse driver that performs a fastening work by rotating a hammer in both forward direction and reverse direction. The electronic pulse driver can provide a fastening force with a small noise although the fastening force is small compared with the impact driver.